mIGF avalable for research?

big_byrd52 · Oct 31, 2003

mIGF available?
I was reading thru some the scientific studies on IGF in the sticky and noticed this:

Our study demonstrates that the integrity and regenerative capacity of total body skeletal musculature is safely extended by local mIgf-1 supplementation into senescence. Even when expressed under the control of strong muscle regulatory elements, the mIgf-1 protein appears to remain in the muscle bed and does not enter the circulation, thereby avoiding hypertrophic effects on distal organs such as the heart, and eliminating risk of possible neoplasms induced by inappropriately high levels of circulating Igf-1. This is in contrast to previous reports in which another Igf-1 isoform expressed pan-fiber specifically in skeletal muscle and heart was detected in the circulation at all ages, causing first physiologic then pathologic cardiac hypertrophy10, 12.

That sounds like some serious complications down the road. There must be mIGF available if they are doing research with it so why dont we use this?

I also read in all that jargon that mIGF causes hypertrophy only in the fast (type IIa) twitch muscle fibers. You can only work the fast twitch fibers by going heavy, correct? this may be a reason why some react better than others but i am sure there are other reasons as well. It just seems that heavy, low rep training would be optimum during IGF use.

hardasschic · Oct 31, 2003

First off, unfortunately we have made very little progress in gene therapy and expressing a muscle specific promoter in a human is a long way off, so don't hold your breath just yet. The implications for this type of delivery are awesome, just not working yet in people and since the few approved cases have lead to a few deaths (in Tx of DS and of childhood cancers), things in that realm of research have been slowed down a lot. I can’t tell you that it won’t make your heart grow, but in dogs [1] there wasn’t an effect on the heart over a lifetime of administration.
As far as affecting type IIa fibers specifically, I'm sure that this isn't a universal phenomenon, if it occurs at all. There is a splice variant (meaning that the gene goes from DNA to 2 different forms of RNA, and thus 2 slightly different proteins) of IGF1 and one increases only transiently after exercise/damage but so far to my knowledge no one has shown that this is a fiber-type specific variant. The study that you may be referring to [2] was in the diaphragm and hasn’t been repeated. Stick with the training that works for you, bro. The scientific community pumps out a lot of mumbo-jumbo, you just have to sift through it and take what can. (Refs below)
HC

1. Molon-Noblot, S., et al., Effect of chronic growth hormone administration on skeletal muscle in dogs. Toxicol Pathol, 1998. 26(2): p. 207-12.
2. Lewis, M.I., T.J. LoRusso, and M. Fournier, Anabolic influences of insulin-like growth factor I and/or growth hormone on the diaphragm of young rats. J Appl Physiol, 1997. 82(6): p. 1972-8.